<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      #d1 {
        width: 200px;
        height: 200px;
        border: 20px solid aqua;
        /* 设置圆角 值越大会越圆，超过宽高的一半时为正圆 */
        border-radius: 200px;
      }

      #d2 {
        width: 200px;
        height: 200px;
        border: 1px solid red;
        /* 给元素添加内边距默认情况下会影响元素的宽高 */
        padding-left: 100px;
        padding-top: 100px;
        /* 设置内边距不影响元素的宽高 */
        box-sizing: border-box;
      }
    </style>
  </head>

  <body>
    <div id="d2">内边距测试</div>
    <div id="d1">边框测试</div>
  </body>
</html>
